Someone over at Socialbakers is going to have to explain this to me very well.
Content Reach and Active users are two different things altogether. Any website can lose active users and still see the content reach or time spent online grow as long as a segment of its users becomes more active.
Also, the data presented is segmented only by age. Other countries may have seen a sharp decrease or even have seen teens use Facebook more.
This does not mean the conclusion is wrong, I just don’t agree with the way it was reached and feel it is questionable.